A while back I noticed there are two signals called RS232_RXD and
RS232_TXD exposed on the PMC connector going to the daughtercard slots
on the USRP. Tracing these back on the USRP schematic, they go to the
Cypress EZUSB chip. I searched around a bit but didn’t find any
reference to any daughtercard using these, nor did grep find any
reference to these in the 3.2.2 release of GNUradio. Is there any way
to send/receive UART data to these lines from within GNUradio? If
not, what was the intent with these lines?